Incremental addition and scale-back of resources adapting to network resource availability

ABSTRACT

An exemplary method includes receiving at a first network a notice of an intended communication to a called party network, wherein the intended communication requires a resource for supporting a streaming data protocol in each network between a calling party network and the called party network; forwarding the notice of an intended communication to a second network and toward the called party network; in parallel with said forwarding, initiating for the intended communication a determination of resource availability for the first network; performing for the intended communication the determination of resource availability for the first network, wherein the determination is for a first resource for the first network; and verifying resource sufficiency for the intended communication. Verification of resource sufficiency is based on resource, (e.g., bandwidth) availability being greater than a threshold for plural network segment of the calling party to calling network required for the intended call.

RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application,“Method And Apparatus For End-To-End Capacity And Priority ManagementThrough Multiple Packet Network Segments”, 61/188,364 filed Aug. 8, 200concurrently herewith. The entire teachings of the above application areincorporated herein by reference.

FIELD OF THE INVENTION

The invention relates to the field of communication systems, and, morespecifically, to a resource control and policy-based managementmechanisms adapted to implement services including priority services.

BACKGROUND INFORMATION

Often, a call may go through several service provider networks in orderto connect from a calling party to a called party. Each serviceprovider's network may include several domains (or administrativeboundaries). In Time Division Multiplexed (TDM) Networks, resourceclearance using signaling messages is supported through serial resourceclearance on a link-by-link basis. In the serial (or sequential) case,no node transmits a message until first obtaining resource clearancewithin its domain. Accordingly, the total time required to set up a callor session with a link-by-link signaling method is O(Σt_(i)) where t_(i)represents the time it takes for resource clearance in the i-th link.

Priority services is the name given to preferred treatment of certainkinds of traffic (e.g., media/data and signaling) over other kinds oftraffic in, for example, the context of civilian or defensecommunication networks. Priority in a public switched telephone network(PSTN) is performed on a switch by switch basis. Calls for priorityusers, such as government entities pass through switches whilenon-priority traffic is blocked.

Three kinds of priority services exist as present; namely, wirelesspriority service (WPS), Government emergency telecommunications services(GETS) by national communications systems (NCS) and multi-levelprecedents preemption (MLPP) by the United States Department of Defense.

GETS provides an ability to preempt calls at a lower priority than MLPP.GETS also provides for buffer-type queuing of a call such that the callwill be the first call to pass when a necessary resource becomesavailable. Call control functionality includes the decision of choosingwhich call to allow and which call to preempt. Resource control andpolicy-based management functionality includes the decision of when topreempt a call or when to buffer-type queue a call.

Within the context of voice, video and other data communications (e.g.,multimedia communications and the like) via packet based networks (e.g.,Ethernet, etc.) resource clearance is handled on a sequential basis.Methods for preemption and priority handling of voice calls andmultimedia services are also lacking in packet based networks.

Summary of the Information

A network element, apparatus and method for combining call admissioncontrol and priority services within different type of networks isprovided. A logical functional entity denoted as a Priority ServicesFunctional Element (PSFE) enables administration of priority servicesand call or session admission control policies through interactions withCall Session Control Function Element (CSCF) and Resource Access ControlFacilities (RACF). Method steps in exemplary embodiments may includeverifying the priority levels, receiving resource availabilityinformation, storing call admission and resource allocation information,identifying path and link information required for an originatedsession, checking available resources at links against required,requested and sufficient resources for the call or sessionestablishment, and communicating resource availability and sufficiencyindication/s (or lack thereof) based on admission control policies afterresource verification.

The PSFE allows for capacity and priority management in parallel overall the links in the bearer path within a particular network. PSFEs indifferent networks can also communicate to enable PSFEs in each networkin the path to perform resource clearance independently and in parallel(i.e., undertaking apparent or actual performance of more than oneoperation at a same time). Proposed methods allow both kinds ofparallelization in networks of different architectures, such as IMS andSIP, and also across varied networks. The PSFE introduces obtainingparallel resource clearance across network boundaries, includingheterogeneous networks. In this manner, calls or sessions may beestablished efficiently, and varied features provided in a multi-medianetwork.

PSFE may use Session Initiation Protocol (SIP) messages to communicatewith Signaling and Service Layer entities, such as Proxy (P-) orInterrogating (I-) CSCFs, Subscriber Information Databases (e.g., HomeSubscriber Server or HSS), and Application Servers (AS). PSFE may alsocommunicate with Transport Layer entities (such as, RACF in an all IMPMultimedia Subsystems (IMS) architecture) using, for example, Diametermessages. However, PSFE may integrate both IMS and non-IMS NextGeneration Service Provider (NGSP) networks and enable efficientresource verification and allocation in the non-IMS NGSP also. Further,the PSFE may also determine resource availability using open loopcontrol or other accounting methods in a network without a RACF.

Parallel resource clearance is useful in establishing variousmulti-media services in all IP-based networks regardless of the types ofusers and may be utilized in Enterprise, Commercial Service Provider,Civilian Government, and Military network segments of IP networks. Incontext of priority services, such a PSFE can provide higher priority topriority service users and queue such users' requests for resourcesahead of resource requests from other, routine users. Priority sessionrequests and associated priority levels can be identified by the PSFE,for example, through Resource Priority Headers (RPH) in the SIP message.It is important to note that to queue priority sessions ahead of routinesessions, no routine session can be allowed in any of the links in thepriority session path. Coordination of such activities across multiplenetwork segments, which is quite complex among CSCFs, Back to Back userAgents (B2BUAs), and Session Border Controllers (SBCs) in separatenetwork segments, can be achieved via communicating PSFEs deployed inthese segments.

Next generation networks may offer various services with multi-mediacapabilities. For example, multi-media point-to-point communication ormultimedia conferencing may be offered. Typically, the media used inmulti-media communications has different bandwidth and performancerequirements. For instance, video services require high bandwidth whiledata communications require lesser bandwidth in general. Further, a usermay be able to use multi-media communications services separately or incombination as per the user need. For example, a user may share awhiteboard or net-meeting with another user exchanging data only or maytalk between themselves at the same time or may even use real-time videocommunications. Multiple users may also participate similarly.

In normal conditions, the communication network has sufficient bandwidthto support any such combination of media services. However, networks maynot have sufficient bandwidth during stressed times, which could occurdue to environmental causes (e.g., earthquake, or tornado) or due tounintended human actions (e.g., fiber cut due to digging) or intentionaland malicious human activities (e.g., hacking, virus, terrorism).Furthermore, networks in the communication path may be bandwidthconstrained such as, wireless networks, or ad-hoc network segments assometimes used in emergency or in tactical war environments. In suchsituations, there may not be sufficient bandwidth to initiate the fullmulti-media service suite. Nevertheless, it may be desirable and prudentto establish the services that can immediately be started based onavailable bandwidth and add the other services as soon as more bandwidthbecomes available. A call-state aware functional element knowledgeableabout transport resource usage is provided to enable resource usageassessment and procurement that permits such incremental resourceaddition.

Several different types of situations, e.g., user addition, mediaaddition, and media quality and capability enhancement, can be addressedthrough such ad-hoc resource addition on availability. With useraddition, users can be added subsequently when there is not sufficientbandwidth to add all desired participants at the start of a conference.For media addition, media types can be added incrementally when there isnot sufficient bandwidth to support all media types requested in acall/session initially For media quality or capability enhancement, whenthere is not sufficient bandwidth to support higher quality and highercapability sessions of a particular media (video or voice) initially,the higher level media may be provided as resources become availablesubsequently. The resource availability may occur from time-to-time fromvarious reasons, including but not limited to, termination of previouslyestablished calls or sessions; restoration of bandwidth through networkmanagement or operations processes; and roaming by a roaming user into anetwork that can provide higher bandwidth. An exemplary resource isbandwidth.

Apparatus and method are provided for capacity and priority managementof a communications network for use in a system having a plurality ofnetworks. An exemplary method includes receiving at a first network anotice of an intended communication to a called party network, whereinthe intended communication requires a resource for supporting astreaming data protocol in each network between a calling party networkand the called party network. The notice of an intended communication isforwarded to a second network and toward the called party network. Inparallel with said forwarding, a determination of resource availabilityfor the first network is initiated for the intended communication. Thedetermination of resource availability for the first network isperformed for the intended communication, wherein the determination isfor a first resource for the first network; and resource sufficiency forthe intended communication verified. For example, resource assessment ofresources sufficient for the intended communication are not queried andreserved sequentially from calling to called party but query andreservation of sufficient resources occurs simultaneously or nearsimultaneously.

In one embodiment, performing for the intended communication thedetermination of resource availability for the first network includesquerying the first resource for the first network for resourceavailability, and receiving a first indication of resource availabilityof the first resource for the first network. In another embodiment,verifying resource sufficiency for the intended communication includesdetermining for the intended communication whether a first indication ofresource availability for the first resource is above a threshold. Inone embodiment, the threshold value corresponds to a media type of theintended communication. In another, the threshold is prescribed by thenotice of intended communication.

Verifying resource sufficiency for the intended communication mayinclude reserving for the intended communication the first resource forthe first network in the event the first resource has resourceavailability above a threshold. In that embodiment, the first resourcemay be reserved at a first level, the first level being greater than thethreshold value and being a minimum of a level of available resource infirst network and a level of resource reserved in the second network.

In another embodiment, verifying resource sufficiency for the intendedcommunication may include receiving for the intended communication fromthe second network a second indication of resource sufficiency of asecond resource for the second network. One embodiment may includeforwarding a re-invite for the intended communication to the secondnetwork and toward the called party network in the event a firstindication of resource availability of the first resource for the firstnetwork is above a threshold and the second indication signifiesresource sufficiency, wherein the first network is the calling partynetwork, thereby indicating resource sufficiency for a correspondingresource in each network from the calling party network to the calledparty network.

One embodiment may include forwarding a request to a transit networkinterposed the first network and the second network for verifying withthe transit network a predetermined Service Level Agreement (SLA) andthat the SLA assures at least one requirement of the intendedcommunication; receiving resource availability information for thetransit network; and forwarding a re-invite of the intendedcommunication to the second network and toward the called party networkin the event a first indication of resource availability of the firstresource for the first network is above a threshold, the secondindication indicates resource sufficiency and the resource availabilityinformation for the transit network is above the threshold, wherein thefirst network is the calling party network, thereby indicating resourcesufficiency for a corresponding resource in each network from thecalling party network to the called party network.

In the event of receipt of a ringing message, one embodiment may forwarda lock message, the lock message instructing that the first resource forthe first network is to be used. Another method embodiment may alsoinclude forwarding a corresponding resource sufficiency message based onthe resource availability information for the first network and theresource sufficiency information for the second network indicatingresource sufficiency for the intended communication. Forwarding acorresponding resource sufficiency message may include forwarding thecorresponding resource sufficiency message within the first network orto a third network. The second network and the third network may be thesame network. For example, the resource sufficiency message may beforwarded within the first network, fed-forward to the second networkand fed-backward toward the calling party network.

In one embodiment, the determination of resource availability for thefirst network is via an open loop control; in another, an accountingbased control is utilized. In one embodiment, the performing for theintended communication the determination of resource availability forthe first network includes communicating with a resource access controlfunction (RACF) to verify the resource availability informationconcerning the first network. An exemplary embodiment may also includeforwarding at least one of a SDPReoffer message or a re-invitationmessage for the intended communication after verifying resourcesufficiency for the intended communication.

In one embodiment, verifying resource sufficiency for the intendedcommunication includes reserving the first resource if its resourceavailability is above a sufficiency threshold, and the method furtherincludes receiving a ringing message and locking the first resource forthe first network that was reserved in response to the ringing message.Another embodiment has a priority indicator included in the notice ofintended communication such that, while verifying resource sufficiencyfor a first intended communication, verifying resource sufficiency for asecond intended communication having a priority indicator less than orequal to a priority indicator for the first intended communication isprevented.

BRIEF DESCRIPTION OF THE DRAWINGS

The teachings of the present invention can be readily understood byconsidering the following detailed description in conjunction with theaccompanying drawings, in which:

FIG. 1 depicts a network topology for facilitating calls through variousnetworks according to an embodiment of the invention;

FIG. 2 depicts an overview of a network topology for facilitating callsthrough an exemplary network according to an embodiment of theinvention; and

FIG. 3 depicts a flow diagram of an exemplary routine according toembodiments in accord with the invention.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures.

DETAILED DESCRIPTION

The subject invention will be primarily described within the context ofvoice calls. However, since the subject invention is directed to thebroader issues of multimedia services (including voice calls) referencesto calls and communications within this specification should be broadlyconstrued to include voice, video, audio, email and other multimediacommunications.

Specific structural and functional details disclosed herein are merelyrepresentative for purposes of describing example embodiments. Exampleembodiments may, however, be embodied in many alternate forms and shouldnot be construed as limited to only the embodiments set forth herein.

The subject invention enables the establishment and management of VoIPtraffic, including traffic of different priority levels, in a network(for example an Internet Protocol (IP) network) with parallel resourceclearance and monitoring of criteria indicative of importance of a newvoice call entering the network, network capability and instantaneousload. Accordingly, an exemplary telecommunications system is describedas one potential environment in which a subject invention operates andexists.

Generally speaking, the invention assists in enabling the followingsystem and network characteristics: (1) A profitable uniformarchitecture that addresses the requirements for both DoD and NCS; (2) Aminimization in the overlap functionality in terms of development andmaintenance of priority service features; (3) A minimization of theimpact on existing architectures; (4) Addressing the requirements of IMSas well as non-IMS environments; (5) An ability to add on priorityservice at any time by a network provider; (6) An interoperability withnetwork solutions of multiple vendors; (7) An ability to pass prioritycalls earlier than routine calls, when a congestion has been cleared andability to maintain “current gets/wps voice functionality” which mayrequire an ability to mimic priority signal queuing from a TDMenvironments; (8) An adaptation to IMS and non-IMS based Next Generationnetworks; (9) An ability to extend and support, at leastarchitecturally, multimedia applications and mid-call features forpriority services in the future; and (10) the providing of calladmission control.

The present invention provides for a logical functional entity denotedas a priority services functional element (PSFE) that integrates withboth IMS and non-IMS networks and environments. Within the context ofnetwork architectures adapted to utilize a PSFE, the PSFE is added tothe architecture as an additional logical entity, such that the rest ofthe network architecture remains substantially unmodified. The PSFEinteracts with the session initiation protocol (SIP) proxies, callsession control functions (PCSCF), resource access control facilities(RACF), (NGSP) and other PSFE entities.

It will be understood that, although the terms first, second, etc. maybe used herein to describe various elements, these elements should notbe limited by these term since such terms are only used to distinguishone element from another. For example, a first element could be termed asecond element, and, similarly, a second element could be termed a firstelement, without departing from the scope of example embodiments. Asused herein, the term “and” is utilized in the conjunctive anddisjunctive senses and includes any and all combinations of one or moreof the associated listed items, and the singular forms “a”, “an” and“the” are intended to include the plural forms as well, unless thecontext clearly indicates otherwise. Unless otherwise defined, all terms(including technical and scientific terms) used herein have the samemeaning as commonly understood by one of ordinary skill in the art towhich example embodiments belongs. It will be further understood thatterms, such as those defined in commonly used dictionaries, should beinterpreted as having a meaning that is consistent with their meaning inthe context of the relevant art and should not be interpreted in anidealized or overly formal sense unless expressly so defined herein.

It is noted that the PSFE can also perform its intended function withoutthe use of a RACF. In that instance, control of specific links isachieved via accounting based methods (whereas control of an entirenetwork is performed with a RACF). In one embodiment, a standard orcommercial network architecture is modified to use a PSFE by providersseeking NCS compliance, though mandatory use of PSFE is envisioned forDoD networks. Optionally, PSFE interaction with H323 systems isprovided. The invention may be utilized within the context of SIP, H323,voice over IP (VoIP) or, more generally, X over IP network (XoIP), whereX is a voice, video or multimedia communication.

The PSFE may provide priority signal message queuing (queuing tracked bylinks of a transport path) and preemption capabilities (i.e., it is ableto identify the calls that need to be preempted to decongest certainlinks). Queuing in this context refers to the buffering-type queuing asis known in the prior art. Queuing in the inventive context is termed bythe inventor as protocol level queuing and includes buffering-typequeuing as well as call state queuing. Queuing a call or other serviceoccurs when, for example, resource availability is verified for a linkduring parallel resource clearance. In this case the call is notdropped; rather, its state is stored by the PSFE until appropriateresources become available for the call in each network to be traversedby the call. Being held or stored means that the state information ofthe call is stored for subsequent use. The state of a call comprises thecall source, the call destination, the resources needed to support thecall, and so on.

Call admission control in a simple form is defined as determining whichcalls should be dropped and which calls should be allowed. Priorityservices in a simple form is defined as providing preferential treatmentto some calls and not other calls. To effectively perform call admissioncontrol and priority services, the network needs to have knowledge ofthe calls in the system, their actual call paths (control plane andmedia plane paths) as well as the transport resources available in thenetwork. One embodiment of the invention includes within one entity (thePSFE), priority and call information (e.g., number of calls in system,available transport resources and the like) needed to combine andcontrol call admission and priority service functions. Thus, the PSFEhelps to simplify network control plane architecture by combiningmultiple priority-related functions (e.g., call admission control andpriority services) in a single functional entity.

The PSFE optionally communicates via Diameter to a RACF. The PSFE mayalso be call-state aware such that it can identify calls over links in atransport network (transport resource aware). In some embodiments, thePSFE continuously polls a RACF to identify availability of resource suchthat resource clearance of multiple call paths may be handledefficiently. In some embodiments the PSFE operates without a RACF (e.g.,for open loop or accounting based controls).

In some embodiments, additional support for the PSFE is beneficial.Specifically, at times it may be appropriate for a RACF to pass linkinformation of a media path (e.g., via a PDFE) to the PSFE. However,this will be needed only under certain cases. RACF link information isnot needed when a call flows or when a priority call is cleared. For apriority call not cleared by the RACF, link information is needed forall subsequent RACF-cleared calls so that the availability of resourcessupporting the non-cleared priority calls can be determined.

Optionally, a P-CSCF (or a Proxy in non-IMS cases) will pass every SIPmessage it receives to the PSFE. Optionally, a new 5xxx message toconvey network attempts (e.g., in the case of priority call queuing) isappropriate. Optionally, a protocol between the PSFE and NGSPs may beadapted to address fault tolerance issues such that fault tolerancefunctionality need not be distributed across a number of CSCFs.

FIG. 1 depicts a network topology facilitating calls through variousnetworks according to an embodiment of the invention. Specifically, FIG.1 depicts an exemplary communications system 100 according to anembodiment of the invention. In addition to architecture, FIG. 1 alsodepicts control and bearer signal paths, which signal paths areassociated with reference numerals indicative of a temporal order ofutilization in establishing and tearing down calls. FIG. 1 will bediscussed in conjunction with other FIGs. to illustrate various callflow examples according to embodiments of the present invention.

Specifically, FIG. 1 depicts a plurality of networks including a callingparty home network 110, a called party home network 120, a calling partyvisited network 130 and a called party visited network 140.

The calling party home network 110 comprises one or more applicationservers (AS) modules 112, a home subscriber server (HSS) 114 and aserving call session control function (S-CSCF) 116.

The called party home network 120 comprises one or more applicationservers (AS) 212, a home subscriber server (HSS) 214, a serving callsession control function (S-CSCF) 116 and interrogating call sessioncontrol function (I-CSCF) 128.

The calling party visited network 130 comprises a P-CSCF 131, a priorityservices functional element (PSFE) 132, a resource allocation controlfunction (RACF) 133, a backbone packet network 136 and an access network137. The RACF 133 includes a policy decision functional element (PD-FE)134 and a traffic resource control functional element (TRC-FE) 135.

The called party visited network 140 comprises a P-CSCF 141, a priorityservices functional element (PSFE) 142, a resource allocation controlfunction (RACF) 143, a backbone packet network 146 and an access network147. The RACF 143 includes a policy decision functional element (PD-FE)144 and a traffic resource control functional element (TRC-FE) 145.

The network 100 FIG. 1 may be modified to represent a conventionalnetwork by removing each PSFE and RACF from the calling and called partyvisited networks. In this case, a call between A and B is initiated inaccordance with the numbered signal paths 1-16; namely (1) a callinvitation is communicated from endpoint A via access network 137 tobackbone packet networks 136, then (2) to P-CSCF 131 and then to (3)S-CSCF, which (4) queries HSS 114, (5) AS 112 and (6) DNS 150 toretrieve the appropriate information pertaining to the called party andits home network. S-CSCF 116 then (7) communicates with the I-CSCF 128of the called party home network. I-CSCF 128 propagates the request (8)to S-CSCF 126, which communicates (9) with its local HSS 124 and (10) AS122 together necessary information regarding endpoint B. S-CSCF then(11) propagates a message to the P-CSCF 141 of the called party visitednetwork 140 associated with endpoint B.

The above steps (1-11) are fairly conventional. In a conventionalnetwork, the P-CSCF 141 communities with a backbone packet network 146to identify those router and other output ports within the RTP streamcapable of supporting the call. This information is propagated back tothe P-CSCF 131. The P-CSCF 131 and P-CSCF 141 cause their respectivebackbone packet networks 136 and 137 provide a communication pathsupporting the call within the RTP stream.

The network 100 of FIG. 1 is depicted as including a PSFE and RACFwithin each of the calling and called party visited networks. Theinteraction of these components with each other and existinginfrastructure will be described in more detail below with respect tothe remaining figures.

Within the context of the present invention, a SIP Proxy (or P-CSCF)continues to work as a transaction-stateful or call-stateless proxy asregards all other features. All calls, independent of priority, to orfrom a SIP Proxy (or P-CSCF) are locally looped to a PSFE. The PSFEoptionally maintains call-state information (including linkidentification information for the traversed links associated with thecall) for all calls. Communications between PSFE and RACF are viadiameter for necessary resource clearance, and various demands andrequests necessary transport path information.

Advantageously, the PSFE enables parallel resource clearance acrossnetwork boundaries, queuing a call in itself until resources becomeavailable. In order to set up calls in parallel across multiple links,the following call control functions are provided: i) call-stateawareness about existing and in-progress calls/sessions; ii) ability togather information regarding resource usages at the links and networkelements, and iii) ability to correlate call path within its domain fromthe addresses. In one embodiment, the PSFE obtains all necessaryresource clearance for a particular call in one parallel operation. ThePSFE performs necessary signal message queuing when it decides thatresources are available with its domain for a call as part of resourceverification. The PSFE routinely polls the RACF to identify resourceavailability. The PSFE sends back appropriate (standard SIP) errormessages to the SIP Proxy (or CSCF) to signal a call that is to beblocked, if need be (e.g., a higher priority call is queued). In theevent of resource sufficiency for the PSFE's own network and receipt ofan indication of resource sufficiency for another network to betraversed by an intended call, the PSFE sends back appropriate (e.g.,standard) SIP protocol messages to the SIP Proxy (or CSCF) to signal acall that is to be allowed. The PSFE initiates 3rd party calling forqueued calls via the P-CSCF, as and when the resources for those callsbecome available. In the case of a 3^(rd) party call, the networkoperates to communicate (i.e., call back) both the calling party and thecalled party at a later time.

While denoted as a realtime transport protocol (RTP) stream in FIG. 1,the backbone packet networks may communicate via any streaming protocol,such as transmission control protocol (TCP), user datagram protocol(UDP) and the like. Signaling messages are sent from the call controlelements in the originating network up to the call control elements inthe terminating network for setting up end-to-end voice, data and videosessions across multiple networks. Different mechanisms for carryingsuch messages can be put in place depending on the network topology,interconnectivity, and protocols supported by the underlying network.

FIG. 2 depicts an overview of a network topology for facilitating callsthrough an exemplary network according to an embodiment of theinvention. A method according to the invention proposes to obtainresource clearance in parallel across all links within a networkboundary, as well as obtain resource clearance across several networkboundaries. A conventional system employs sequential resource clearance,in which no node transmits a message until that node first obtainsresource clearance within its domain. (i.e., serial resource clearanceis accomplished on a link-by-link basis). In contrast, in parallelresource clearance as provided by the PSFE, the apparent or actualperformance of more than one resource clearance operation occurs at atime, by the same or different devices and modules. In the parallelcase, the various time requirements for resource clearance (Ti) aretriggered as and when a resource availability request is received indomain i, and the domain i does not wait for the completion of Ti beforesending a resource availability request to domain i+1. In this manner,multiple domains may be obtaining resource clearance without having towait for the completion of resource clearance in a previous one/s. Whenthere are multiple links in each domain, resources clearance within adomain may also be performed in parallel. For example, by using PSFEsfor obtaining resource clearance in parallel across all links within anetwork boundary, as well as obtaining resource clearance across severalnetwork boundaries, the time required for resource clearance will bereduced to O(Max(t_(i))), where Max(t_(i)) represents the maximum of allt_(i), i.e., the maximum of all individual resource clearance times inindividual links. Accordingly, the time required to process and transmita message in a PSFE enabled network is much lower than the time requiredto wait for clearance on all links in a conventional network.

Such a methodology leads to one or more benefits. For example, settingup calls and sessions across an IP network will be more efficient andfaster, which will reduce post-dial delay. Calls and sessions will havehigher probability to complete set-up protocol exchanges before anyparticular timer expires, such as during set up when the networks arecongested. For an end-to-end call which encounters multiple serviceprovider (SP) networks, each SP network may be provided with informationon resource needs and priority for the call/session, and the separatenetworks are able to assess and clear the calls. The time for set up ofa call or a session that crosses several network domain boundaries(resulting from reasons, such as, administrative domains, geographicaldistribution, and population density, etc., even within a same SPnetwork) will require only the maximum time required for setup in any ofthe domains.

Further, beneficial applications can be developed using the methodologyprovided. For example, the resource needs and priority assignment fromthe originating network/user may be communicated globally in a trustedmanner with private mapping of such priority assignments at eachseparate network for specific internal usage within each network asdescribed in U.S. patent application Ser. No. ______ entitled RHPMapping And Defaulting Behavior, filed December XX, 2008, which isherein incorporated by reference. Many call scenarios require connectionto media servers, at times prior to call establishment and in othercases in mid-call, and the access path to media server may differ fromthat carrying the bearer packets from the caller to the called. Theproposed methodology enables reservations and resource management acrosssuch different paths in parallel. In addition, the methodology providedfacilitates the establishment of multiple call legs, where call legs foran intended communication may include legs for each end point (end pointreferring to users, media server, conferencing server, and the like) andfor each media type (e.g., video, audio, text, data, and the like, andsome combination thereof) and some combination thereof. For example, ifcapacity is constrained to support all media types in a multi-mediacall, reservations across media types in parallel can be utilized toenable early establishment of calls with one media requiring lessercapacity when required capacity to support all media types isunavailable at the start of a call between calling parties or aconference call among multiple endpoints. Later, other media types canbe added when capacities become available to support them. Similarly,resources may be scaled back in case of bandwidth constraint occurringafter session establishment so long as connectivity is still establishedand services, even though reduced, are still offered. The necessity forresource reduction may occur for reasons reverse to those described withrespect to resource addition, such as, traffic surge, network disruptionfrom hardware and software cause/s, and roaming of a wireless networkuser into networks with limited capability.

An overview of the mechanism for the parallel resource clearance by PSFEacross multiple networks is outlined in FIG. 2. Further detail may befound described in U.S. patent application Ser. No. ______ entitledEnd-To-End Capacity And Priority Management Through Multiple PacketNetwork Segments, filed December XX, 2008 which is herein incorporatedby reference. For example, in FIG. 2, a call may be initiated from acaller at network A to a called end at network C and will traversenetwork 200, which comprises networks A 210, B 220 and C 230.Alternatively stated, a call initiated from a caller to a called endwill traverse networks N₁, N₂, N₃, N_(i), . . . N_(M), where N₁ is thehead end, and N_(M) is the tail end of the call. The head end refers tonetwork components like proxies, CSCF and PSFEs closest to the caller,while tail end refers to those network components closest to the calleduser. Also note that only three networks, namely A, B and C areillustrated for simplicity.

Each network includes a CSCF (212, 222, 232), a PSFE (212, 224, 234), aRACF (216, 226, 236), and a backbone packet network (218, 228, 238). Thebackbone packet network in each network may include a plurality ofservers (219, 229, 239). The RACF may include a policy decisionfunctional element (PD-FE) and a traffic resource control functionalelement (TRC-FE) (not shown)

All calls, independent of priority, to or from a CSCF are locally loopedto a PSFE. The PSFE maintains call-state information (including linkidentification information for the traversed links associated with thecall) for all calls. Communications between PSFE and RACF are viaDiameter for necessary resource clearance, and various demands andrequests necessary transport path information.

When a call passes through networks A, B and C, then the PSFE element ineach of those network clouds is responsible for obtaining necessaryresource clearances in its own network respectively. In parallel withthe verification of resource availability within its network, the PSFEforwards the notice of an intended communication to the next network andtoward the called party network. As resources become available at leasta sufficient level in each of the networks, the PSFEs in that networkawait for the clearance to arrive from the tail end of the call. Inother words, network B waits for the clearance from network C, andnetwork A waits for the clearance from network B. Thus, network A willnot receive clearance until both networks C and B have at leastsufficient resources for the call. At this point the PSFE in network A,communicates to the CSCF in network A (or the SIP proxy in network A)and triggers a re-invite from the caller to the called user. In analternative embodiment, PSFEs in each of the networks await for theresource clearance indication to arrive from the head end direction ofthe call.

In each of these network segments one or multiple PSFE communicates withthe corresponding CSCF and RACFs. For example, if resource clearance ispropagated toward the tail end, on receiving a new session or callrequest through SIP INVITE and from the identification that the call orsession needs to be forwarded to the CSCF in Network B, the PSFE inNetwork segment A forwards a resource assessment request to PSFE inNetwork segment B, while looking into the resource requirement versusavailability in Network segment A. The PSFE in Network segment A alsofollows up with a message to the CSCF and PSFE in network segment Bregarding resource availability above the sufficiency threshold inNetwork segment A after its determination.

The PSFE in Network segment B performs the same function as the PSFE inNetwork segment A, which is sending a resource assessment request toPSFE in Network segment C by recognizing that the call or session needsto be sent to Network segment C while it gets engaged in verifyingresource availability in Network segment B. PSFE in Network segment Balso follows up with a message to the CSCF and PSFE in Network segment Cregarding resource availability above the sufficiency threshold. Themessage to Network segment C is based on resource availability above thesufficiency threshold in Network segment B after its determination andthe resource availability/sufficiency determination message that Networksegment B received from PSFE in Network segment A. The minimum level ofresource available across both Network segment A and Network Segment Bmay be messaged to Network segment C

The CSCF in Network segment C determines that the called end is inNetwork segment C. PSFE in Network segment C determines the resourceavailability for the requested call or session for the Network segment Cand together with the availability message received from PSFE in Networksegment B, determines the level of end-to-end resource availabilitybefore informing its decision on call or session admission to the CSCFin Network segment C. CSCF in Network segment C then admits or disallowsthe call based on PSFEs' decision (based on resource availabilityinformation that indicates resource sufficiency for PSFEs in A, B andC). The process repeats until the call is upgrade to the initiallyrequested resource level.

In an exemplary embodiment, the described process may be utilized forresource addition resulting in addition of conference participants. Forexample, a user-A may originate a request for conferencing with 3 otherparticipants, users B, C, and D. The call request message is sent toPSFE from the CSCF for assessing resource availability against needs andPSFE determine that resources are available to support one calledperson, but not three. In that event, PSFE indicates to CSCF to proceedwith call set-up between user-A and user-B, and waits for resourceclearing to add the other users. As other calls end, PSFE grabs theresources cleared and indicates to CSCF to proceed with adding otherusers to the conference if sufficient resources have become available.

Such a capability can be used in many different ways. For example, incommercial carrier networks, in one exemplary use, user-A may indicateparticipants who are minimally required for the conference to begin andadd other optional users as resources become available. In anotherexemplary use, user-A may indicate a preferred order of users to beadded, e.g. by individual and by group identifications. Further detailsrelated to such embodiments are described in U.S. patent applicationSer. No. ______ entitled Network Call Back To Add ConferenceParticipants And/Or Media, filed December XX, 2008, which is hereinincorporated by reference. These capabilities are useful in context ofpriority services as PSFE can provide higher priority to priorityservice users and queue those users requests ahead of resource requestfrom other routine users. The priority session requests along withassociated priority levels can be identified by the PSFE for example,through the Resource Priority Headers (RPH) in the SIP message.

Incremental addition of media types is another situation where resourceaddition on availability finds utility. For example, a user-A mayinitiate a request for simultaneous voice, video, and data sessions withusers B and C. As the request is forwarded from CSCF to PSFE forclearance, PSFE determines that there is only sufficient bandwidth forthe voice session but not for video conferencing and white-boarding. Inthat event, the PSFE indicates to CSCF to initiate the voice conferenceand queues the resource request for the other media types. As othersessions terminate, the PSFE grabs the resources cleared and indicatesto CSCF to proceed with adding other white-boarding and videoconferencing sessions. Similarly, the PSFE provided may be utilized forsessions of same media that may be started with lower quality and lowercapabilities and subsequently the sessions are upgraded to improvedquality and capabilities as resources become available.

Moreover, scale-back of resources can be achieved when network resourcesare incrementally diminished following a similar resource assessment,comparison, notification, and agreement. Such capabilities are desirablewhen calls/sessions with diminished capabilities are preferable thandropping the call/session altogether.

In other embodiments, a transit network may be interposed two of theNetwork Segments illustrated (e.g., between Network segments A and B,Network segments B and C). A transit network is used for bulk transportbetween networks providing user services. Such transit networks providebulk transport services only and do not have call or session managersassociated therewith but may honor Service Level Agreements (SLA), whichare primarily based on statistically averaged call or sessionperformance over time. SLAs are generally based on connectivity metricssuch as, downtime, reliability and availability measures, and bytessent/received, and Quality of Service metrics such as, delay, delayvariation, packet loss and packet throughput.

Transit networks do not provide individual call or session control andmanagement. Thus, the transit network and its partners will typicallyhave an overall bulk transport carrying agreement but the transitnetworks do not support specifically any individual call or sessionrelated characteristics. For example, a transit network may be outfittedwith a PSFE, RACF and a Backbone network but not have a CSCF.

For calls passing through such core transport networks or transitnetworks, obviously call or session management is not performed by thecore transport service provider. Thus, the originating and/orterminating network service provider on either side of the transitnetwork is responsible to provide end-to-end call or session admission,and management. Accordingly, the PSFE also is enabled to negotiate anddetermine resource availability from the transport-only networks. Inaddition, as described above, the PSFE performs resource assessment inits own network and forwards a resource assessment and clearance requestthrough SDP offers to PSFEs in the call path as determined from thedestination URI. Based on received the availability information for itsown network and other networks in the call path including any interposedtransit networks, a PSFE decides on call admission and instructs theCall Session Control Function Elements (CSCF) for implementing call orsession admission decisions.

FIG. 3 depicts a flow diagram of an exemplary routine according toembodiments in accord with the present invention. The call blocking callflow, call queuing and call creation for the parallel resource clearanceof 300 of FIG. 3 will be described within the context of thecommunications system 200 of FIG. 2. Specifically, control signal pathsbetween calling endpoint-A 302 in network A (i.e., calling partynetwork) and called endpoint-C of network C (i.e., called party network)as can be gathered from FIG. 2 comprise, in the order named, CSCF-A 212,PSFE-A 214, CSCF-B 222, PSFE-B 224, CSCF-C 232, PSFE-C 234.

Referring now to FIG. 3, at 301 an invite message is propagated fromcalling endpoint A to CSCF-A 212, then at 302 to CSCF-B 222, and finallyat 303 to CSCF-C 232. In general, each network sends an invite messagetoward the called network until the called network is reached by thenotice of intended communication.

In parallel with the propagation of the invite message, each PSFE (214,224, 234) verifies resource availability for a resource required for theintended communication (e.g. local estimate of resource availability at316, 318, 320 and 322). When an invite message enters a first network(e.g., network C), the corresponding PSFE (e.g., PSFE-C 234) attempts toreserve necessary resource for the call and queues the call in itsstack. The corresponding PSFE (e.g., PSFE-C 234) may determine fromcorresponding RACF (e.g., RACF-C 236 not shown in FIG. 3) if resourcesare available for all the links within the first network (e.g., networkC) for this particular call. In one embodiment, if requested resourcesare not available, the call is queued, and no lower or equal prioritycall is allowed until this particular call gets a chance to obtain therequested resource capacity.

For example, in the case of dynamic real-time bandwidth management, todetermine if corresponding resources are available, corresponding RACF(e.g., RACF-C 236) listens to the SNMP messages from multipleswitch/routers in that network (e.g., network C) in parallel anddetermines if all the necessary link/s that constitute the call haveenough resource/s available or at least a minimum percentage of therequested resource is available. The minimum fractional part orsufficiency threshold of the total resource requested (F_(min)) may bepreviously provisioned per service type or may be specificallyprescribed by the SDP Reoffer. If resource Res_(i) is available innetwork i, and Res_(i) is a fraction of the requested resource Res,i.e., Res_(i)=Fi*Res is available (such that, F_(min)<Fi<=1), thencorresponding PSFE holds this resource and waits for confirmation fromdownstream PSFEs. For instance, the requested resource may be bandwidth.In that case, if bandwidth Bi is available in network i, and Bi is afraction of the requested bandwidth B (i.e., Bi=Fi*B is available) suchthat, F_(min)<Fi<=1, then corresponding PSFE holds this bandwidth andwaits for confirmation from downstream PSFEs.

For example, in FIG. 3 at 316, PCFE-C determines that a bandwidth of 100bits-per-sec is available in network C. The availability of resource ina network is determined as the available resource greater than a minimumrequired for the call (B_(m)>=F_(min)*B where F_(min)*B or B_(min) isreferred to as the absolute minimum bandwidth/resource that is requiredby the network to accept a call. This absolute minimum may be differentfor different media types, codecs, QoS, etc.

If the PSFE is in the called party network (e.g., network C), theresponse may be forwarded based on resource availability within thecalled network alone. Since Network C is the tail end network, PSFE-Cpropagates a response 317 to PSFE of the previous one of the networkstoward the head end network, when resources are available at least asufficient level. Similarly, at 318, PCFE-C determines that a bandwidthof 150 bits-per-sec is available in network C as and when the resourcebecomes available and propagates at 319 a resource availability messageindicative of resource sufficiency in network C toward the calling partynetwork.

In cases where dynamic bandwidth management is not required and merecall counting or bandwidth counting will suffice, the corresponding PSFEor the corresponding RACH may be directly involved in bandwidth or callcounting and determine the availability of the necessary resource/s. Theact of queuing the call and communication with the corresponding RACHensures that resources are obtained in parallel in that network (e.g.,network C). In case of dynamic bandwidth management, all correspondingrouters in the network may send updates in parallel to the correspondingRACH of that network. The corresponding PSFE then makes decisions basedon the query to the corresponding RACH of the network as describedabove.

For PSFE deployed in other than the tail end network, the correspondingPSFE (e.g., PSFE-B) waits for the response availability message whichindicates a resource sufficiency from the next PSFE toward the tail end(e.g., PSFE-C), and which arrives via corresponding CSCFs. The PSFEforwards a “resource held” message after it has received the resourceavailability response indicative of resource sufficiency from the PSFEcorresponding to the next network towards the called party (i.e.,PSFE_(i+1)) and determined that the available resource in its ownnetwork is greater than some threshold as described above. The “resourceheld” message can be implemented as an 1xx message. Thus, for PSFE in afirst network other than called party network (i.e., intermediatenetworks (e.g., network B) and the calling party network (e.g., networkA)), a “resource held” message is forwarded if each network from firstnetwork in question to the called party network have resourceavailability for the intended communication. Again, the “held” messageis delivered toward the head end PSFE via the corresponding CSCF of thefirst network and the network next closest the head end network.

For example for an exemplary resource such as bandwidth, the bandwidthsignaled in the “resource held” message is a resource availabilityresponse indicative of resource sufficiency and indicative of theminimum of the bandwidth available for each network from the networkcorresponding the PSFC_(i) making the current determination of resourcesufficiency to the called party network. For example, if the bandwidthin the response from PSFC_(i+1) is B_(i+1), then PSFC_(i) responds toPSFC_(i−1), with the value MIN(B_(i), B_(i+1)) (i.e., the minimumbetween B_(i) and B_(i+1)).

According, at 320 PSFE-B determines that 80 bps is available in networkB. This determination is performed in response to the reserve message312 and thus in parallel with resource determinations at other networksfrom the calling party network to the called party network. Then forinstance, after simultaneously or near simultaneously receiving resourceavailability message 319 from the tail end, PSFE-B determines theend-to-end availability is 80 bps, the minimum of 80 bps available innetwork B and 150 bps available in network C. At 321 PSFE-B forwards a“resource held” message indicative of the available resource that hasbeen determined, with the available resource at least above a threshold.The determined available resource may be the absolute minimum resourcethat is required by the network to accept a call. In this manner, a PSFEsends a “resource held” toward the next PSFE closer to the head-end PSFEonly when the resource in all subsequent networks are available for theintended call at least a threshold level. A “resource held” message isessentially a command that instructs the CSCF that resources are heldfor a user, but are not yet consumed. The Held message may beimplemented as a 1xx message.

As resources become available in each of the networks, the PSFE in eachnetwork await for the clearance to arrive from the tail end of the call.In other words, when a call passes through networks A, B, and C, B waitsfor the clearance from C, and A waits for the clearance from B. Thus, Awill not receive clearance until both C and B have necessary resources.All the intermediate networks' PSFE and the final network PSFE sends a1xx message indicating that resources are held when the resources becomeavailable.

In another embodiment, a transport network may be interposed for examplenetworks B and C, the PSFE of the network closer the head end network'sPSFE (B) learns about the network where the call/session needs to beforwarded to (i.e., network C) and the intermediate transport network(B′) from the called URI. The PSFE then verifies the SLA agreed with thetransport network (B′) and determines if the SLA assures at leastminimal requirements for the call/session in progress. The originatingnetwork's PSFE utilizes this information to determine if the transportnetwork has resource availability or at least a minimum percentage ofthe request resource is available for the transit network. Thus, in suchan embodiment, PSFE-B also has verified that the transport network B′can assure the resources required in B′ through communication with thetransport network.

In an alternate embodiment, the PSFE sends an indication of resourceclearance head-end as soon as resources are determined to be availablein its own network and the decision about final call admission may bebased on resources availability across the various networks asdetermined by the PSFE at the head end network (i.e., calling partynetwork).

When head end PSFE (e.g., PSFE-A) receives the response back from thenext PSFE toward the tail end (e.g., PSFE-B), the head end PSFE triggersthe corresponding CSCF to initiate a SIP Re-Invite (an SDP Reoffer) tothe called end with the currently available bandwidth across all linksend-to-end (B_(avl)). As described above, B_(avl) will be the minimum ofbandwidth available in each network. (B_(avl)=MIN (B₁, . . . B_(M)).B_(avl) is also greater than or equal to the absolute minimum resourcerequired to accept the call (B_(avl)>=B_(min)). In FIG. 3, PSFE-Breceives a propagated “resource held” message 321 indicative of theavailable resource that has been determined for all subsequent networks.At 322, PSFE-B determines at 322 that the end-to-end availability is 80bps, the minimum of 80 bps available in subsequent networks and 200 bpsavailable in local calling party network A. At 323, PSFE-B forwards a“resource held” message indicative of the available resource that is atleast above a threshold level.

In response to a “resource held” message, CSCF-A initiates a SIPRe-Invite to the called end at 324 and the Re-Invite is forwarded allthe way up to the called end via the CSCFs at 325 and 326. On receivingthe Re-Invite, the called end processes the call/session per itscondition. If the call/session is accepted, then a “ringing” message issent upstream toward the next calling end CSCF. Each CSCF (CSCF_(i))sends a “ringing” message upstream to its next upstream CSCF(CSCF_(i−1)). Alternatively, an SDPReoffer may be triggered for adetermination of end-to-end resource sufficiency.

Each CSCF_(i) also sends a “lock” message (328, 329, 330) to itsPSFE_(i) on receiving the “ringing” message from downstream CSCF_(i+1)so that minimum of bandwidth available across each network (B_(avl)) isnow dedicated for this session/call. The “lock” message ensures thenecessary resource is locked in using the queued information associatedwith the call via lock message. A Lock message is essentially a commandthat instructs the PSFE that resources are now being used. The Lockmessage may be implemented as another 1xx message or could bepiggybacked with ‘ringing’ message. Prior to the PSFE receipt of theLock message, the call is merely queued and the resources are not beingconsumed. Messages need not be in SIP, but can be implemented inDIAMETER or any other protocol.

It is noted that the minimum of the bandwidth available across each ofthe networks (B_(avl)) becomes the starting bandwidth available for thecall as indicated by 340. Accordingly, each PSFEi updates resourceavailability as the difference between bandwidth determined availableand bandwidth now dedicated for this call (Bi=Bi−B_(avl)).

If a PSFE in any network held bandwidth greater than the amount nowdedicated (Bi>=B_(avl)), the extra bandwidth is held in reserve untilreceipt of another message from a subsequent PSFE toward the tail end(PSFE_(i+1)) that updates (i.e., provides) a newly available bandwidthfor the subsequent network/s. In one embodiment, this newly availablebandwidth is strictly greater than the older value of resourceavailability known for the PSFEi and is due to each PSFEi comparing itsresource availability with resource availability from downstream (e.g.,by comparing B_(i) with B_(i+1)), and sending a message with updatedadditional availability only if there is resource availability on bothnetworks (i.e., B^(new) _(avl)=MIN(B_(i), B_(i+1))>0; and as ultimatelydetermined at the head end B^(new) _(avl)=MIN (B^(new) ₁, . . . B^(new)_(M))>0). Otherwise additional resource availability is held at eachPSFEi.

If the head end PSFE (i.e., PSFE₁; PSFE-A) determines that additionalbandwidth can be assigned to a particular call/session as per itsoriginal demand, the head end PSFE triggers the corresponding CSCF toinitiate another SIP Re-Invite (or SDP Reoffer) to the called end withthe currently available bandwidth. The tail end PSFE (i.e., P_(M);PSCF-C) accordingly will realize that the available bandwidth in itsnetwork is now B^(new) _(M). This value of B^(new) _(M) may bedetermined such that it is greater than previously known B_(M), by atleast a pre-defined percentage.

The steps described are repeated until the call is upgraded with thenewly available bandwidth as conditions permit.

A similar process is followed for scaling back resources instead ofadding resource. The communication among the PSFEs, CSCFs, and RACFs,will be similar with the same messages utilized. A new invite messagewill be forwarded by PSFE-A of the calling party network, every time aresource constraint appears and a PSFE communicates the need for newreduction of resources. Resource are scaled back to use currentlyavailable resources, which are the minimum of resource availabilityacross each of the networks (B^(new) _(avl)=MIN (B^(new) ₁, . . .B^(new) _(M))).

The PSFE of the present invention advantageously isolated Parallel CallAdmission and Priority Services development so that such services areeasier to develop and maintain. Moreover, such services may now beprovided without service and software replication with respect to vendorproduct offerings. Parallel Call Admission and Priority Services can bean optional service required by a customer and can fit IMS and non-IMSnetworks, including H323. With the novel PSFE, newer DISA and NGPSfeatures are easier to develop. In this manner, new features like“priority conference call reservation” of priority conferences may beimplemented. In addition, the PSFE relieves the burden of having a CSCFor any other fully operational SIP Proxy maintain resource awareness(i.e., call states with respect to links). The PSFE provides resourcecontrol and policy-based management mechanism adapted to implementpriority services in a packet network environment, such as describedherein.

The above-described embodiments of the invention may be implementedwithin the context of methods, computer readable media and computerprogram processes. Generally speaking, methods according to theinvention may be implemented using computing devices having a processoras well as memory for storing various control programs, other programsand data. The memory may also store an operating system supporting theprograms. The processor cooperates with conventional support circuitrysuch as power supplies, clock circuits, cache memory and the like aswell as circuits that assist in executing the software routines storedin the memory. As such, it is contemplated that some of the stepsdiscussed herein as software processes may be implemented withinhardware, for example as circuitry that cooperates with the processor toperform various steps. Input/output (I/O) circuitry forms an interfacebetween the various functional elements communicating with the device.

A computing device is contemplated as, illustratively, a general purposecomputer that is programmed to perform various control functions inaccordance with the present invention. The invention also can beimplemented in hardware as, for example, an application specificintegrated circuit (ASIC) or field programmable gate array (FPGA). Assuch, the process steps described herein are intended to be broadlyinterpreted as being equivalently performed by software, hardware and acombination thereof in various alternative embodiments.

The invention may also be implemented as a computer program productwherein computer instructions, when processed by a computer, adapt theoperation of the computer such that the methods and/or techniques of thepresent invention are invoked or otherwise provided. Instructions forinvoking the inventive methods may be stored in fixed or removablemedia, transmitted via a data stream in a signal bearing medium such asa broadcast medium, and/or stored within a working memory within acomputing device operating according to the instructions.

While not specifically noted, it will be appreciated by those skilled inthe art that various network management system (NMS) and elementmanagement system (EMS) are used to manage the various functionalelements discussed herein, including the new PSFE. Each PSFE is managedby an appropriate NMS and/or EMS, which is selected according to thenetwork within which the PSFE operates. Thus, the PSFE is operable toprovide bridge and information and protocol bridge between variousmanagement systems such that call state aware and priority state awareinformation may be utilized throughout a large group of networks, asdiscussed above.

Within the context of a NMS or EMS utilizing the present invention, aninstantiation of an application such as an IMS application includes aPSFE that is logically and/or physically disposed between the RACF andCSCF of a network to perform the various functions discussed above. Assuch, one embodiment of the invention comprises a method for adapting acontrol plane of a communication network normally using a call sessioncontrol function (CSCF) in communication with a resource access controlfunction (RACF), where the method includes providing a priority servicefunctional element (PSFE) between each RACF and its corresponding CSCFto verify a priority level for each call, receive resource allocationinformation from the RACF, store a resource allocation for each call,and cause the CSCF to preferentially allocate resources to high prioritycalls as discussed above with respect to the various figures.Instantiations supporting the PSFE may be provided on a single server ormultiple servers, and/or within a single network or multiple networks.

An apparatus according to the invention is adapted for use in a systemcomprising a plurality of networks, each of which include a resourceaccess control function (RACF), a call session control function (CSCF)and a packet network supporting, illustratively, a Realtime TransportProtocol (RTP) stream between the calling and the called party networks.The PSFE advantageously provides a knowledge of call-states as well asthe “links” that they pass through, in order to block routine calls(e.g, NCS and DoD applications), queue priority calls against the“links” that they will use (e.g., NCS applications) and teardown/preempt calls, under certain conditions, based on the “links” thatthey traverse (e.g., DoD applications). The PSFE also provides anability to perform 3^(rd) party calling (network initiated) when queuedcalls are processed, and an ability to obtain “link” (i.e., transportresource paths) information from certain elements in the network. Thisinformation is then passed to the relevant management system.

Reference herein to “one embodiment”, “another embodiment” or “anembodiment” means that a particular feature, structure, orcharacteristic described in connection with the embodiment can beincluded in at least one embodiment of the invention. The appearances ofthe phrase “in one embodiment” in various places in the specificationare not necessarily all referring to the same embodiment, nor areseparate or alternative embodiments necessarily mutually exclusive ofother embodiments. Although various embodiments which incorporate theteachings of the present invention have been shown and described indetail herein, those skilled in the art can readily devise many othervaried embodiments that still incorporate these teachings.

1. A method comprising: receiving at a first network a notice of anintended communication to a called party network, wherein the intendedcommunication requires a resource for supporting a streaming dataprotocol in each network between a calling party network and the calledparty network; forwarding the notice of an intended communication to asecond network and toward the called party network; in parallel withsaid forwarding, initiating for the intended communication adetermination of resource availability for the first network; performingfor the intended communication the determination of resourceavailability for the first network, wherein the determination is for afirst resource for the first network; and verifying resource sufficiencyfor the intended communication.
 2. The method of claim 1 whereinperforming for the intended communication the determination of resourceavailability for the first network comprises: querying the firstresource for the first network for resource availability; receiving afirst indication of resource availability of the first resource for thefirst network.
 3. The method of claim 1 wherein verifying resourcesufficiency for the intended communication comprises: determining forthe intended communication whether a first indication of resourceavailability for the first resource is above a threshold.
 4. The methodof claim 3 wherein the threshold corresponds to a media type or qualityof service for the intended communication.
 5. The method of claim 3wherein the threshold is prescribed in the notice of intendedcommunication.
 6. The method of claim 1 wherein verifying resourcesufficiency for the intended communication comprises: reserving for theintended communication the first resource for the first network in theevent the first resource has resource availability above a threshold. 7.The method of claim 6 wherein the first resource is reserved at a firstlevel, the first level greater than a level corresponding to thethreshold, and the first level a minimum of a level of availableresource in first network and a level of resource reserved in the secondnetwork.
 8. The method of claim 1 wherein verifying resource sufficiencyfor the intended communication comprises: receiving for the intendedcommunication from the second network a second indication of resourcesufficiency of a second resource for the second network.
 9. The methodof claim 8 further comprising: forwarding a re-invite for the intendedcommunication to the second network and toward the called party networkin the event a first indication of resource availability of the firstresource for the first network is above a threshold and the secondindication signifies resource sufficiency, wherein the first network isthe calling party network, thereby indicating resource sufficiency for acorresponding resource in each network from the calling party network tothe called party network.
 10. The method of claim 8 further comprising:forwarding a request to a transit network interposed the first networkand the second network for verifying with the transit network apredetermined Service Level Agreement (SLA) and that the SLA assures atleast one requirement of the intended communication; receiving resourceavailability information for the transit network; and forwarding are-invite of the intended communication to the second network and towardthe called party network in the event a first indication of resourceavailability of the first resource for the first network is above athreshold, the second indication indicates resource sufficiency and theresource availability information for the transit network is above thethreshold, wherein the first network is the calling party network,thereby indicating resource sufficiency for a corresponding resource ineach network from the calling party network to the called party network.11. The method of claim 1 further comprising: in the event of receipt ofa ringing message, forwarding a lock message, the lock messageinstructing that the first resource for the first network is to be used.12. The method of claim 1 further comprising: forwarding a correspondingresource sufficiency message based on the resource availabilityinformation for the first network and the resource sufficiencyinformation for the second network indicating resource sufficiency forthe intended communication.
 13. The method of claim 12 whereinforwarding a corresponding resource sufficiency message comprises:forwarding the corresponding resource sufficiency message within thefirst network.
 14. The method of claim 12 wherein forwarding acorresponding resource sufficiency message comprises: forwarding thecorresponding resource sufficiency message to a third network.
 15. Themethod of claim 12 wherein the second network and the third network arethe same network.
 16. The method of claim 1 wherein performing for theintended communication the determination of resource availability forthe first network is via at least one of an open loop control and anaccounting based control.
 17. The method of claim 1 wherein performingfor the intended communication the determination of resourceavailability for the first network comprises: communicating with aresource access control function (RACF) to verify the resourceavailability information concerning the first network.
 18. The method ofclaim 1 further comprising: forwarding at least one of a SDPReoffermessage or a re-invitation message for the intended communication afterverifying resource sufficiency for the intended communication.
 19. Themethod of claim 1 wherein verifying resource sufficiency for theintended communication includes reserving the first resource for the ifresource availability is above a sufficiency threshold, the methodfurther comprising receiving a ringing message; and locking the firstresource for the first network that was reserved in response to theringing message.
 20. The method of claim 12 wherein the notice ofintended communication includes a priority indicator, the method furthercomprising, while verifying resource sufficiency for a first intendedcommunication, preventing verifying resource sufficiency for a secondintended communication having a priority indicator less than or equal toa priority indicator for the first intended communication.